Fuel cell technology

A fuel cell converts the chemical energy of a fuel directly into electricity without first burning it to produce heat.64 It is similar to a battery in its construction. Two electrodes (Figure 11.24) are separated by an electrolyte which transmits ions but not electrons. Fuel cells possess high theoretical efficiency. Typical efficiencies in practice are in the range of 40-80%.

Hydrogen for fuel cells may be supplied from a wide variety of sources, from coal65 or other biomass (see Note 31), from natural gas,66 or from the hydrolysis of water using electricity generated from renewable sources such as wind power or solar photovoltaic (PV) cells (see box on page 364).

Figure 11.25 Remote area power system, employing hydrogen and fuel cell technology, supplying energy to a New Zealand farming community from a hill top wind turbine 2 km away. Electricity from the wind turbine is used to generate hydrogen by electrolysis of water. A polymer pipe 2 km long conveys the hydrogen to a fuel cell and/or hydrogen burner so providing heat and power to the farming community. The pipe not only provides a cheap way of transporting energy but also, by allowing pressure in the pipe to vary, provides a useful amount of hydrogen storage.

Figure 11.25 Remote area power system, employing hydrogen and fuel cell technology, supplying energy to a New Zealand farming community from a hill top wind turbine 2 km away. Electricity from the wind turbine is used to generate hydrogen by electrolysis of water. A polymer pipe 2 km long conveys the hydrogen to a fuel cell and/or hydrogen burner so providing heat and power to the farming community. The pipe not only provides a cheap way of transporting energy but also, by allowing pressure in the pipe to vary, provides a useful amount of hydrogen storage.

into fuel cells in recent years that has confirmed their potential as an important future technology. Although several technical challenges are yet to be resolved, there is an expectation that fuel cells will come into widespread use within the next decade.

Hydrogen for fuel cells can be generated from a wide variety of sources (see box). The most obvious renewable source is through the hydrolysis of water using electricity from PV cells exposed to sunlight or from wind turbines - an efficient process, over 80% of the electrical energy can be stored in the hydrogen. There are many regions of the world where sunshine or wind is plentiful and where suitable land not useful for other purposes would be readily available. The cost of electricity from PV or wind sources has been coming down rapidly (Figure 11.18) - a trend that will continue with technological advances and with increased scale of production. The IEA BLUE Map scenario assumes significant penetration of hydrogen fuel cell vehicles into the transport sector well before 2050.

Hydrogen is also important for other reasons. It provides a medium for energy storage and it can easily be transported by pipeline or bulk transport. An efficient local rural application is shown in Figure 11.25. For larger and more general applications, the main technical problem to be overcome is to find efficient and compact ways of storing hydrogen. Present technology (primarily in cylinders at high pressure) is bulky and heavy, especially for use in transport vehicles. A number of other possibilities are being explored. Other technologies for local energy storage, for instance, flywheels, super capacitors and superconducting magnetic energy storage (SMES), are also being actively explored.67 As the

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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